Details of a plot to kill Occupy Houston leaders won’t be released after a federal court upheld the FBI’s claim that the documents are legally exempted from the Freedom of Information Act.

The FBI argued information was withheld, including 12 of 17 relevant pages, to protect the identity of confidential sources who were “members of organized violent groups,” according to Courthouse News Service.

A heavily-redacted FBI document first revealed a Houston plot “to gather intelligence against the leaders of the protest groups and obtain photographs, then kill the leadership via suppressed sniper rifles.”

However the plotter’s identity is redacted.

Ryan Shapiro, a graduate student at Massachusetts Institute of Technology and historian, filed several requests for documents pertaining to the Houston plot in 2013. In response, the FBI said they had no such relevant records, so Shapiro sued, accusing the bureau of an inadequate search.